The development of hemoglobin-based oxygen carriers has focused on oxygen delivery for use in medical therapies such as transfusions and the production of blood products. Hemoglobin-based oxygen carriers can be used to prevent or treat hypoxia resulting from blood loss (e.g, from acute hemorrhage or during surgical operations), from anemia (e.g., pernicious anemia or sickle cell anemia), or from shock (e.g, volume deficiency shock, anaphylactic shock, septic shock or allergic shock).
Existing hemoglobin-based oxygen carriers include perfluorochemicals, synthesized hemoglobin analogues, liposome-encapsulated hemoglobin, chemically-modified hemoglobin, and hemoglobin-based oxygen carriers in which the hemoglobin molecules are crosslinked. Preparation of hemoglobin-based oxygen carriers includes several purification steps. Among the components that must be removed from collected blood is fibrinogen, which is a soluble protein that is converted into fibrin by the action of thrombin during clotting. Current techniques for processing blood often include addition of chemical agents, such as sodium citrate, to prevent coagulation. However, additional techniques which might, for example, reduce the expense of processing, without diminishing other qualities, such as ultimate product purity, are sought.
The present invention relates to the use of defibrinated blood for purifying red blood cells, preparing a hemoglobin solution, and preparing a hemoglobin-based oxygen carrier. Chemical clotting agents (such as collagen) and mechanical agitation (such as stirring) are methods used to defibrinate blood. Subsequent cell washing removes plasma proteins that may lead to incompatibility between donor and recipient blood.
In one embodiment, the method for purifying red blood cells includes defibrinating whole blood, the whole blood including red blood cells and a plasma component. Subsequently, the whole blood is filtered to purify the red blood cells and thereby form a red blood cell suspension.
In an embodiment of the method for preparing a hemoglobin solution, whole blood is defibrinated. Red blood cells are separated from the whole blood, and hemoglobin molecules are isolated from the red blood cells to form thereby a hemoglobin solution.
In one embodiment of the method to prepare a hemoglobin-based oxygen carrier, whole blood is defibrinated. Red blood cells are separated from the whole blood. Hemoglobin molecules are isolated and stabilized to form the hemoglobin-based oxygen carrier.
The advantages of this invention are numerous. One advantage is that the invention obviates the need for an anticoagulant solution to be mixed with whole blood (human, bovine, mammalian). Adding an anticoagulant involves manpower and capital for the processes of preparation of high purity water mixing solutions, preparation of citrated collection containers, collection, mixing, and purification. In addition, when shipping blood, generally it is easier to defibrinate blood than it is to build facilities for addition of an anticoagulant at the shipper""s location.